Should You Use Lead-Reducing Fuel Additives?

An Aeronca 7AC Champ aircraft. [FLYING Archive]

Q: I fly a Champ with a Continental C-85 engine, and I am confused about the benefits of fuel treatments like TCP that reduce lead deposits from 100LL. My spark plugs look clean. Is it just a good idea to use lead-reducing fuel additives anyway?

A: There is no secret about the harmful effects of lead. I recently spoke with George Braly of General Aviation Modifications Inc. (GAMI), who is currently running tests for their unleaded avgas alternative G100UL. Initial teardowns of the tested powerplant showed cleanliness far superior to that of leaded 100LL. Lead is a dirty business, a foul element (no pun intended), and better left to history.

Aircraft Spruce & Specialty carries a wide range of lead-reducing additives, including TCP. While we cannot review each one individually, one key indicator to look for when choosing an aircraft product is FAA approval. It is always a good idea to stay in line with the feds.

Alcor’s TCP stands for tricresyl phosphate, which is an effective tetraethyl lead (TEL) scavenger. It is rated for many types of powerplants and requires no additional approvals. The company claims it will reduce plug fouling. You mention in your question that you typically do not have an issue with fouled plugs. Are you considering TCP as a preventative measure? If so, a lead reducer like TCP Fuel Treatment could be an effective way to bridge the gap until more inclusive unleaded avgas approvals are signed.

100ll fuel additives lead

Richard ScarbroughAuthor

Richard is a US Navy Veteran, A&P Mechanic, and Embry-Riddle Aeronautical University alumni. His experience ranges from general and corporate aviation to helicopters, business jets, and commercial airliners. Former owner of a 145 repair station, he currently has an aerospace product management role and is a member of the T-C-Alliance. Follow him on X (Twitter) at @RScarCo.